Rail brake for drafting machines and the like



G. R. SNURR 3,194,348

RAIL BRAKE FOR DRAFTING' MACHINES AND THE LIKE July 13, 1965 Original Filed July 25,v 1959 ATTORNEY United States Patent O 3,194,348 RAIL BRAKE FOR DRAFTING MAC 2 AND TIE LIKE Gordon R. Snurr, Franklin, Pa., assignor to Glideline Corporation, Wayuesboro, Pa., a corporation of Pennsylvania Original application July 23, 1959, Ser. No. 828,984, now Patent No. 3,131,478, dated May 5, 1964. Divided and this application May 8, 1963, Ser. No. 278,909

6 Claims. (Cl. 188-67) My invention relates broadly to rail brakes and more particularly to a rail brake for drafting machines and the like for selectively locking a drafting machine part, such as a protractor assembly, in selected position on a drafting machine rail.

This application is a division of my copending application Serial No. 828,984, filed July 23, 1959, now Patent No. 3,131,478, granted May 5, 1964, for Protractor for Drafting Machine.

One of the objects of the invention is to provide a simple construction of rail brake which provides positive nonslip locking engagement with a cylindrical rail and which can easily be moved into and out of locking engagement with the rail.

Another object of the invention is to provide a novel construction of rail brake which is rugged in construction and provides positive means for maintaining the same in locked and unlocked position.

Another object of the invention is to provide a construction of rail brake in which the locking member is movable in two planes.

A further object of the invention is to provide a construction of rail brake for a drafting machine protractor in which the protractor assembly is selectively locked to the drafting machine vertical rail by a simple spring biased pivoted lock ring disposed about the rail and cocked at acute angles with respect to the rail into engagement with the vertical rail.

Other and further objects of the invention reside in the novel construction of rail locking mechanism as set forth more fully in the specification hereinafter following by reference to the accompanying drawings, in which:

'FIG. 1 is a side elevational view of the rail brake assembly of the invention, with parts shown in phantom and showing a fragmentary portion of a drafting machine protractor connected thereto;

FIG. 2 is a transversesectional view through the rail locking mechanism showing the mechanism in the unlocked position;

FIG. 3 is a view taken substantially along line 33 of FIG. 2;

FIG. 4 is a cross-sectional view taken substantially along line 44 of FIG. 2; 7

FIG. is a transverse sectional view taken substantially along line 5-5 of FIG. 2, with the rail shown in elevation;

FIG. 6 is a cross-sectional view, similar to FIG. 4, but

showing the rail brake or rail lock mechanism in the locked position;

FIG. 7 is a transverse sectional view similar to FIG. 5 but showing the rail brake in locked position;

FIG. 8 is a top plan view of the lock ring member of the rail locking mechanism;

.FIG. 9 is a side elevational view of the lock ring member of FIG. 8; and

FIG. 10 is a cross-sectional view taken on line 10-10 of FIG. 9.

This invention is directed to a construction of rail brake wherein a rail passes through a housing having a bearing lined bore such that the only connections between the housing and the rail are rolling ball bearing contacts. At one end of the bored housing, or protrusion from a housing, a rail brake or rail locking mechanism is provided to securely lock the housing at any desired point along the rail. This is accomplished by cocking a spring-loaded lock ring, which encircles the rail, at an acute angle to the rail so as to grip the rail and prevent any movement between the housing carrying the lock ring, through a pivotal connection, and the rail.

Referring to the drawing in greater detail, the housing of a protractor assembly or the like is designated at 1 carrying the bored protrusion 1a for engagement with the vertical rail 2 of a drafting machine. The protractor assembly is arranged to travel up and down the vertical rail 2 of the drafting machine, but it is to be understood that the protrusion 1a can have any type member con-v nected to it which is to be locked to rail 2 and that the rail brake of the invention set forth herein is described in association with a drafting machine rail and protractor assembly merely for purposes of illustration. To provide smooth glading movement for the protractor assembly as it travels along the vertical rail the interior bored portion of the protrusion 1a carries ball bushing units (not shown) secured therein and disposed between the rail 2 and the housing protrusion In. These ball bearing units carry ball bearings which provide rolling contact between the protrusion encircling the rail and the rail, the ball bearings being arranged to insure a smooth slide fit without shake or play as the unit travels along the rail. These ball bushing units preferably contain precision nylon ball bearings, thus eliminating the necessity of lubrication, insuring longer life and providing a quieter operating drafting machine. In applications other than drafting machines the protrusion 1a may be slidably connected to the rail by other suitable bushings, bearing means, or the like.

The top end of bore protrusion 1a is substantially closed around the circumference of thevertical rail by spring plate 3 secured to the interior of the bore. The clearance provided between spring plate 3 and rail 2 is very slight so that the spring plate can also act as a rail wiper for removing large particles of eraser dust, etc, from the rail and thus prevent its entrance into the ball bushing units and the rail brake or rail locking mechanism.

The rail brake or locking mechanism of the invention is located adjacent the spring plate, interiorly of the bored protrusion 1a, and consists of brake or lock ring 4, lock ring guides 5 and 6, verticallock springs 7 and lock or brake acutating lever 8. Lock ring 4 provides slots 9 and 1t), off-center with respect to each other with one end of the slots in registration, through the side walls thereof for slidable engagement with lock ring guides '5 and 6 which are secured in the walls of protrusion 1a and protrude outwardly into the interior bore thereof into slots 9 and 10, respectively, of the lock ring. The top surface of the lock ring provides recessed mounting holes 11 for springs 7, with the bottom surface of spring plate 3 providing similar mounting holes oppositely situated from those on the lock ring 4, and springs 7 are mounted in a compressed state between the spring plate and the lock ring in the respective mounting holes provided thereon.

Lock lever 8 is threaded into the side of the lock ring opposite the mounting holes 11 and protrudes through the irregular shaped opening 12 in the side wall of protrusion 1a as more clearly shown in FIG. 3. Irregular shaped opening 12 provides a high abutting edge 12a for lever 8 for the locked position of the locking mechanism as shown in FIGS. 1 (dotted), 6 and 7, and a low abutting edge 12]) for lever 8 when the same is depressed and rotated to the unlocked position of the rail locking mechanism as shown in FIGS. 1-5. In the locked position lever 8 abuts the edge 12a of opening 12, guides 5 and 6 are moved to a position in the ends of slots 9 and 10 by counter-clockwise rotation of the lock or brake ring, as shown in 6, and. springs '7 exert a downward force on lock ring 4 and pivot it about guides 5 and 6 tea cocked position against rail 2 as shown inFIGS. 6 and 7. The springs 7 thus hold thebrake or lock ring rigidly against the vertical rail in such a manner that the housing which carries the-lock'ring is rigidly locked from movement'with re-.

spect to the rail 2.i The interior edges of the lock ring are left sharp to enable them to grip rail 2 and thus hold the assembly connected thereto in an immovable position with respect to the rail, while the exterior edges of lock ring 4 are rounded to enable it to be cocked sideways in thebore of protrusion 1a without catching on theinterior side wallsthereof.

To unlock the housing carrying the rail brake from its locked position-on the rail, the lever 8 is pushed. downward and rotated slightly clockwise to a position as shown in FIGS. 2-5. In this position the lock ring 4 has been.

pivotedabout guides 5 and 6 into a substantially horizontal position,-thus further compressing springs 7. As the lock ring is rotated clockwise by lever 8, lever 8" comes into contact with the edge 12b of opening 12. and

is held in abutment with this edge by the downwardly directedforce of springsL. The clockwise movement of lock ring 4 positions the guides 5 and 6 to approximately the centerposition of clots 9and-ltl as shown in FlGg4,

and moves the mounting holes-for springs 7 in spring plate 3 and lockring .4 off-center with respect to ,each.

other thus putting a curve in the springs as shownin FIG. 5.' In the unlocked position the interior edges of lock ring 4-are moved outof contact with the vertical relation and laterally offset relative to. each other forjen-I gaging said lever; arm andmaintaining the' same in serail and the protrusion'la and assembly connected thereto are free to travel up and down or along the rail.

, :The rail brake mechanism of the invention has been constructed and used on drafting machines and has been ''found to be very rugged, useful,;efficient,reliable, easy to manipulate and unyieldable inthe locked state under 7 normal operating conditions.

While the rail brake or lock ring assembly of'the invention has been described in certain preferred embodiments itis realized that modifications can be made-and it is to be understood that no limitations upon the invention are intended other than which may be imposed-by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States, is as follows;

V l 7 -4 2. A rail brake asset forthlock ring containselongated slo'ts in opposite sidewalls thereof for pivotal engagement and' rotative 'slidingfen gagernent with said pair of pivotalguide means} 1 a V 3. A rail brake.as;set"forth in' clairn 1' 'n which said means for maintaining said lock ring inengagementiwithsaid-rail consists offlbias springs extending betweenisaidj housing and said locklring, said,bias sp'ringsextending in; a plane' substantially parallel withthe'rail and havingends each other upon rotatior'tz adapted to be 'oflset relative to' of thelock ring.

4. A rail brake as set; forth gaged position.

5. A rail-brake'lasi setforth'in claim.' 1 :inlvvhich said means connectedrfor zpivoting saidilock rin ont of-engagement ,with 'the rrail consists-ofa lever armextending from said lock ring-,1 said housing havingan irregular shaped opening, said lever and extending through the ir regular-shaped opening," andsaid irregular-shaped opening having abutting limit 1stop'edges in loingitudinal spaced lected positions upon rotation' ots aid ring. V

V and rotative movement to said: lock finemberflrelative to said pivotal guide-elements to move saidlock member out i of locking engagement with the railto allowlfree; travel of said housingfalong the rail and maintairirit'ina disenf gaged position against the urging ofsaid means connecte d -l. [A rail brake fora rail comprising, a housinghaving interior walls disposed adjacentthe rail, a pair of pivotal guide means extending from the interior walls of said housing, a lock ring encircling the rail, said lock ring en-. gaged by said'pair of pivotal guide means wherebysa'id' lock ringis adapted to pivot longitudinally ofthe rail' 7 and rotate laterally, means connected: with said lojck ring for pivoting and resiliently maintaining said lock ring in engagement with the rail to securely lock the hous-v ing' to the rail, means connected between said ,lock ring and said housingqfor pivoting said lock ring out of en. gagement' with the rail and laterally rotating said lock ring on said pair of pivoted guide means to .connectisaid ring to said, housing formaintaining the lock ring in a disengaged position. 5 a

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,, r FOREIGN-PATENTS}; 24172 f 2/26 Great Britainzy "589,028 a 2/59 Italy. I

with'said lock member. 7 References Citedhy theExaii inergi UNITED STATES PATENTS 7 7 957,409; 10 49 1 France,

in claim 1 tin which said" I v inYclaim 11in.whichfsaidq]; V lock ringis rotatable in'aplane substantially perpendicu- 7 lar with the railto maintainsaid lock ring in thedisen- 

1. A RAIL BRAKE FOR A RAIL COMPRISING, A HOUSING HAVING INTERIOR WALLS DISPOSED ADJACENT THE RAIL, A PAIR OF PIVOTAL GUIDE MEANS EXTENDING FROM THE INTERIOR WALLS OF SAID HOUSING, A LOCK RING ENCIRCLING THE RAIL, SAID LOCK RING ENGAGED BY SAID PAIR OF PIVOTAL GUIDE MEANS WHEREBY SAID LOCK RING IS ADAPTED TO PIVOT LONGITUDINALLY OF THE RAIL AND ROTATE LATERALLY, MEANS CONNECTED WITH SAID LOCK RING FOR PRIVOTING AND RESILIENTLY MAINTAING SAID LOCK RING IN ENGAGEMENT WITH THE RAIL TO SECURELY LOCK THE HOUSAND SAID HOUSING FOR PIVOTING SAID LOCK RING OUT OF ENAND SAID HOUSING FOR PIVOTING SAID LOCK RING OUT OF ENGAGEMENT WITH THE RAIL AND LATERALLY ROTATING SAID LOCK RING ON SAID PAIR OF PIVOTED GUIDE MEANS TO CONNECT SAID RING TO SAID HOUSING FOR MAINTAINING THE LOCK RING IN A DISENGAGED POSITION. 